Some excuses used by customer to get free or cheap photos would seem wrong in other businesses, why not for photographers ?

The photography market has to face some hard times, there is nothing new with that.
Pro photographers that are trying to sell their images are facing all kinds of excuses from their customers who are trying to get the pictures for free or at least for cheaper than the normal rates.

Here are some arguments that are often used by potential customers :
« We don’t have a budget for the picture, but we will publish it with your name, that will be a huge advertisement for you »
« We want a deal (discount or free), so that we can test you. If we are satisfied we will use you again at the regular price »
…

While surfing I found a small video on Youtube where these arguments are used but for other businesses than photography.
Looking at this video, it seems so wrong to ask that kind of deal in a restaurant or at the DVD store.
If it’s wrong for a restaurant why should it be accepted in the case of the photographers ?